Measure the thickness of the shelf and take note of the location of any premarked mounting holes on the shelf.
Place strips of masking tape onto the wall where you wish to locate the shelf, recreating the shelf thickness with the tape. Place marks on the tape with a pencil at the locations of the mounting holes, or at the locations where you intend to place the shelf mounting brackets. Try to locate your shelves so that you can install the mounting brackets directly into wall studs. Locate the wall studs using a stud finder.
Mark bracket locations if no premounting holes are present by placing the end brackets about 10 inches from the shelf edges, and then placing a bracket every 12 inches between the end brackets along the length of the shelf. Verify that the masking tape is level using a carpenter’s level. This ensures that the shelf will be level once installed.
Place the mounting brackets against your chosen locations with the tops of the brackets level with the marked shelf bottom. Mark the bracket holes on the wall using a pencil. If attaching the shelf to a masonry or concrete wall, install anchors for screws in the marked holes. Predrill the anchor holes using a hammer drill and then tap the anchors into the predrilled holes using a hammer until the anchors lie flush with the surface of the wall. Choose your anchors according to the supported weight and an estimate of the weight you intend to place on the shelf.
Place the mounting brackets against the wall with the holes aligned with the marks or anchor holes. Secure the brackets to the wall by inserting a screw through the bracket holes and screwing it firmly into the wall studs or wall anchors with the electric screwdriver. Continue until you have secured all brackets.
Remove the masking tape and place the shelves onto the brackets. Using an electric drill, predrill starter holes for the screws through the bracket holes into the shelves. Secure the shelves into place using flat-head screws. Choose screws compatible with the shelf material and shorter than the shelf height to avoid the screws protruding from the top of the shelf.